Electrical ignition system



ELECTRICAL IGNITION SYSTEM Filed Nov. 13, 1967 2 Sheets-Sheet 1 44 4Lazy? 7 (61 r 7 9 1,? J0 J0 United States Patent Ofi ice 3,476,492Patented Nov. 4, 1969 3,476,492 ELECTRICAL IGNITION SYSTEM Harold G.Roberts, Medinah, Ill., assignor to Chicago Dryer Company, Chicago,Ill., a corporation of Illinois Filed Nov. 13, 1967, Ser. No. 682,116Int. Cl. F2311 /20 US. Cl. 431-71 2 Claims ABSTRACT OF THE DISCLOSURE Aspark is discharged adjacent the first burner tip of a gas burner tubedisposed in the main ironing cylinder of a gas-heated ironer or thelike. Simultaneously, a combustible gas-air mixture is passed into thetube and the mixture is ignited at one end of the tube having aplurality of spaced burner tips disposed along the length thereof. Atime delay relay is also energized simultaneously. A flame rod disposedover the terminal burner tip completes a circuit as flame surges fromsuch tip, thereby stopping the sparking and placing the system inautomatic operation. If flame does not reach the flame rod within thetime set by the relay, the fuel input into the burner is terminated bythe relay, and a safety switch terminates the sparking action shortlythereafter.

BACKGROUND OF THE INVENTION Field of the Invention This inventionrelates to improvements in controls for gas-fired burners such as areemployed in commercial ironers and the like.

Prior Art The prior art although cognizant of the necessity of safetycontrols for burners of combustible mixtures as in US. Patent Nos.2,503,260 and 2,563,230, fails to provide the flexibility of control andcomplete protection which present day commercial machinery demands forsafety and convenience of operation. The prior art devices of the typehereinafter disclosed generally comprise a fixed arrangement ofcomponents which cannot be altered, or altered only with difficulty, tomeet varying conditions of operation. In addition, normally a singlesafety device adapted to interrupt the supply of nonignited fuel isemployed rendering safety of operation dependent upon the properfunctioning of a single element.

SUMMARY OF THE INVENTION It is an object of this invention to provide acontrol for a gas burner such as may be incorporated in a commercialironer or the like in which the passage of a combustible gaseous mixtureinto a burner is automatically and precisely controlled whereby thepossibility of dangerous accumulation thereof without ignition iseliminated by the action of a plurality of safety circuits, which avoiddangerous gas accumulation and ignition of that gas which hasaccumulated.

It is another object of the provided control to provide a flexibility ofoperation whereby the control may be readily set to provide optimumsafety in burners of varying design and capacity.

It is yet another object of this invention to provide a burner controlcomposed of a minimum number of readily available parts which provideautomatic ignition and continuous operation in complete safety withoutthe necessity of constant surveillance.

In one illustrative embodiment indicating the manner in which theprovided invention functions, a heated roll of an ironer employs aburner tube extending along the length of the interior thereof with aplurality of burner tips arranged at intervals along the length of thetube. A control comprising this invention, including a sparkingelectrode spaced from a ground strip disposed adjacent the first burnertip, is adapted to ignite the gaseous fuel of the burner in completesafety.

Subsequent to the closing of a starter switch, an ignition transformeris energized to form a spark between the electrode and ground strip. Afuel valve is opened, passing a combustible air-gas mixture into theburner tube. The spark ignites the gas emerging from the first burnertip, and flame passes from tip to tip until the gas emerging from theterminal tip is ignited.

Also energized simultaneously is a time delay relay which is adapted toclose the fuel control valve unless the gas emerging from the burnerterminal tip is ignited within a pre-set time interval.

A flame rod disposed above the terminal burner tip electricallycommunicates with the time delay relay upon impingement thereagainst offlame heat. If all of the burner tips are ignited within the safe timeinterval prescribed by the relay, the sparking is terminated and thefuel control valve allowed to remain open. Subsequent operation is thencontrolled by a thermostat.

If for any reason flame from the terminal burner tip does not engage theflame rod within the time dictated by the relay, the fuel valve willclose and shortly thereafter a seperate safety switch will warp outbreaking the circuit energizing the electrode transformer. The lattersafety switch will operate soon after the time delay relay and thuscomprise a second safety device preventing ignition after the gas feedhas terminated.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view of a gasheated flatwork ironer adapted to utilize the safety control of thisinvention;

FIG. 2 is a view similar to FIG. 1 depicting the opposite side of theironer illustrated in FIG. 1;

FIG. 3 is a fragmentary sectional view partly broken away of the heatedironing roll utilized in the ironer of FIGS. 1 and 2; I

FIG. 4 is a left end view of the roll of FIG. 3;

FIG. 5 is a right end view of the roll of FIG. 3; and

FIG. 6 is a schematic wiring diagram relating to the safety controlutilized in conjunction with the ironer of FIGS. 1 and 2.

Referring now more particularly to FIGS. 1 and 2, a gas heated flatworkironer 10 is illustrated which is sold by the Chicago Dryer Company ofChicago, 111., and identified by Model No. GA16. The sheets or otherlinens to be ironed are placed on feed ribbons 12 schematicallyillustrated, which carry the items under a finger roll 14, see FIG. 2,and two padded compression rolls 16 which, being driven at a higherspeed of rotation than main ironing roll 18, tend to smooth the itembeing ironed, eliminating all wrinkles as the sheet is driven betweenthe padded rolls 16 and the larger heated ironing roll 18. The ironeditem may be discharged onto a table 20 disclosed at the feed end of themachine or it may be discharged by means of a lower conveyor 22 onto areceiving platform 24 disposed at the rear of the machine.

FIG. 1 illustrates basic elements utilized in the Chicago .Dryer IronerModel GA16, including a main drive motor 26 which drives a main drivegear 28 through an intermediate gear box 30. The drive gear meshes withlarge gear 32 connected to the main heated ironer roll 18. Gear 32rotatably drives in opposite directions of rotation, gears 34 connectedto the padded compression rolls 16 whereby the main ironer roll 18rotates in a direction opposite that of rolls 16, also gears 32 and 34may be driven by a chain also engaging drive gear 28.

FIG. 2 illustrates a blower motor 36 which forces a predeterminedmixture of gas and air into a burner tube 38 more clearly seen in FIG. 3Also illustrated in FIG. 2 is an overlying exhaust hood 40 which, inconjunction with a blower motor 42 and ductwork 44, is adapted toexhaust products of combustion which are produced by the burner tube 38from the vicinity of the ironer. The heated ironer roll 18 is open atopposed ends as is more clearly seen from FIGS. 4 and 5 and thereforethe products of combustion resulting from the burning of gases forcedinto burner tube 38 are not retained within the roll 18. Accordingly inthe normal course of ironer operation both blower motor 36 which feedsthe fuel into the burner tube 38 and blower motor 42 which exhausts theproducts of combustion from the vicinity of the ironer must beoperating.

It has been common practice, utilizing gas heated ironers such as thatdepicted in FIGS. 1 and 2 of the drawing, to employ a constantly burningpilot light for purposes of igniting the fuel which is forced into theburner tube 38 as by means of the illustrated blower motor 36. However,this practice has proved unsatisfactory from a safety standpointinasmuch as on occasion one or more of the discharge openings or burnertips, such as openings 46 illustrated in FIG. 3, become clogged,resulting in an accumulation of non-ignited gas in a specific locationwithin the roll 18.

Assuming that a constantly lit pilot light was disposed adjacent theleft hand end of the burner tube 38 of FIG. 3, in the event that one ormore of the discharge openings 46 were clogged, preventing a uniformjumping of the flame from left to right as the gas is discharged fromthe unclogged openings 46, a rather large volume of gas may accumulatein the right hand end of the roll before contact is made with suchflame, resulting in an explosion. Inasmuch as some of the rolls 18 maybe 8 feet in length, or greater, the hazard inherent in the use of aconstantly burning pilot light for igniting the gas emerginguncontrolled from the burner tips 46 such as those illustrated on tube38 is apparent.

In accordance with this invention, an electrical ignition system hasbeen provided which assures the safe ignition of the gas which is beingfed into the burner tube of an ironer roll within a desired time limitsuch as five seconds or the like. If ignition has not commenced at theend of such prescribed safety period, the supply of fuel gas into theburner tube is automatically cut off preventing any dangerousaccumulation of gas which could lead to an explosion in the manner abovedescribed. An additional safety element will de-energize the ignitingmeans shortly after the supplying of gas has terminated.

In FIG. 3 there is illustrated an electrode 50 maintained at a desiredinterval from a ground strip 52. The latter strip extends over theinitial discharge tip 46i of the burner tube 38 in the manner moreclearly seen in FIG. 4, comprising a left end view of the apparatusillus trated in FIG. 3. In the normal course of operation, a highvoltage spark will be discharged between the tip of the electrode 50 andthe ground strip 52 at the same instant that gas and air are beingforced into the burner tube 38 by means of the blower motor 36. Assumingthat there is no obstruction in any of the burner tips 46, the sparkcreated between the electrodes 50 and 52 will ignite the gas emergingfrom burner tip 461 and flame will jump from left to right until gasemerging from a terminal tip 46: is ignited. A heat sensitive element orflame detector 48, see FIG. 5, is disposed over discharge tip 46t, andupon having a flame impinge thereagainst, will send a signal to a relayterminating sparking between the electrode 50 and strip 52.

Simultaneously with the initiation of the sparking over the burner tip46i, a time delay relay is energized which is set for a predeterminedperiod of time within which the flame must reach the flame detector 48.If the flame does not reach the detector within the prescribed period oftime, a solenoid of a fuel valve such as valve 54 illustrated in FIG. 2is de-energized to close the valve and immediately terminate the feedingof fuel into the burner tube 38. The fuel which has passed into theburner tube during this interval is inadequate to create a damagingexplosion. A safety switch will subsequently terminate sparking shortlyafter closing of the valve 54, and the attendant in the vicinity of theironer will than have an opportunity to immediately examine the burnertube in complete safety for purposes of determining the cause of thefailure of the flame to reach the flame detector 48 within the timeperiod dictated by the time delay relay.

For a fuller understanding of this invention reference will now be madeto the schematic wiring diagram of FIG. 6 which is illustrative ofcircuitry which maybe employed in effecting the desired control of theelectrical ignition system of this invention. The following steps arecarried out in utilizing the ignition system of this invention. Astarter button 60 conveniently disposed on the ironer frame is pushedclosing the contacts of relay 61 and starting blower motor 36, the hoodor canopy motor 42 and the main drive motor 26. Safety switch or fingerguard 63 must be in the closed condition to enable the ironer to operateand is opened when an attendant feed ing items into the ironerinadvertently allows her fingers to approach the heated roll 18 therebytripping a safety bar which opens switch 63.

Disposed in the conduit 55 suppling the air to the burner tube 38 is afuel pressure switch 64; disposed in the ductwork in which the gases ofcombustion are exhausted by the canopy motor 42 is a canopy pressureswitch 66. These two switches are closed only when there is a gaseousflow, thereby assuring proper functioning of the blower motor 36 whichfeeds the fuel into the ironing roll 18 and the exhaust motor 42assuring efficient discharge of the gases of combustion from the hood 48to the exterior of the building in which the ironer is disposed.

Simultaneously with the starting of three motors, power is applied totransformer 68 comprising a component in a protection relay 70 which iscommercially available under Model No. RA 890E from the HoneywellCompany of Minneapolis, Minn. The energized transformer 68 causes avacuum tube in electronic net-work 72 of the relay 70 to heat upenergizing a flame relay 74 comprising coil 1 and normally closedcontacts F1 and F2 and normally open contacts F3 and F4 controlledthereby. The flame relay closes a check relay comprising coil C andnormally open contacts C1. When the check relay is energized a signal isapplied to the electronic network 72 which de-energizes the flame relay.A check current may then pass through the normally closed contacts F1,and assure the closed condition of the above mentioned switches 64 and66 in addition to the closed condition of gas control switch 73 whichassures that the gas feed line is open, thermostat 76 and temperaturelimit switch 78, all five of said switches being in series as depicted.

If all five switches are closed, then the relay 84, comprising coil Land normally open contacts L1 and L2, is energized allowing current toenergize the solenoid of gas valve 54, thereby opening the same. Currentis allowed to pass to the valve 54 through the closed contacts L1 ofrelay 84, closed contacts of time delay relay 86 and the closed contactsK1 of relay 96. Thus, simultaneously with the opening of the gas valve54, time delay relay 86 is energized making it necessary for the flameto reach flame detector 48 within the time period prescribed by therelay 86 or the closed contacts thereof will be opened, breaking thecircuit to valve 54, closing the same.

Current also passes to the ignition transformer 90 through contacts L1and F2 thereby initiating sparking between electrode 58 and strip 52 asthe gas valve 54 is opened and the time delay relay 86 is energized. Thetime delay relay is commercially available under Model No. 10337H192-Eand is sold by the Cutler Hammer Company of Milwaukee, Wis.

Assuming that the flame, initiated by the spark gap between electrode 50and strip 52 progresses along the length of the burner tube 38 so as toreach the burner tip 46t and engage flame detector 48 within the timeperiod necessary to open the contacts of the time delay relay 86, asignal is sent by the flame detector 48 to the electronic network 72again energizing the flame relay 74. With this energization, relay 84drops out and the current to the ignition transformer 90 which hadpreviously passed through normally closed contacts F3 is terminatedstopping sparking between the electrode 50 and ground strip 52.

As contacts F2 are opened, contacts F3 are closed and current passagethrough contacts K1 of relay 96 permits energization of coil K of relay96 which is commercially available under Model No. 488G from theHoneywell Company of Minneapolis, Minn. The latter relay permitscontinued energization of the coil of the solenoid in the gas valve 54by current flow through contacts K2 inasmuch as the time delay relay 86has now dropped out as a result of contacts L1 opening upon energizationof the flame relay 74 and the subsequent de-energization of the coil Lof relay 84. When relay 84 becomes de-energized, energization of relay96 through contacts L1 is prevented, but energization of the latterrelay is accomplished through contacts F4.

The gas valve 54 will remain open and combustion will continue until thetemperature within the ironer roll 18 attains the maximum temperatureallowed by thermostat 76. When this occurs, the switch of thermostat 76will open and the gas valve 54 will close and remain closed until thelower temperature for which the thermostat is set is reached and switch76 again closes. Inasmuch as the five switches 64, 66, 74, 76 and 78will once more be closed in series, a repetition of the sparkingoperation will take place resulting in reignition, assuming the sameoccurs within the time period prescribed by the time delay relay 86 inthe manner above described. The temperature limit switch 78 comprises anauxiliary safety device disposed adjacent the surface of ironing roll 18which assures closing of the gas valve in the event of any malfunctionof the thermostat 76 which is adapted to ride on the ironer rollsurface. Such malfunction may prevent breaking of the circuit by thethermostat while maintaining the gas valve 54 in the open position at anelevated temperature.

In the event that the flame detector 48 does not transmit a signal tothe electronic network 72 within the time limit dictated by the timedelay relay 86, the time delay relay contacts will open breaking thecircuit energizing the solenoid which maintains the gas valve 54 in theopen position. Inasmuch as the flame relay 74 will not then becomeenergized as a result of any signal emitted by the flame detector 48,the operation of the ignition transformer 90 will then be terminated byheating element 95 which will continuously heat safety switch 97 untilthe latter switch comprising a bimetallic element warps, breaking thecircuit through the switches in series, and de-energizing the relay 84and thereby closing contacts L1 and terminating energization of theignition transformer. The contacts of switch 97 must be manually closedafter element 95 and switch have cooled.

It is seen therefore that a novel system has been provided for ignitinga gas heated ironer in complete safety without any danger of a fuelaccumulation which could perhaps result in an explosion which could bedamaging. The provided system allows flexibility in operation, inasmuchas a specific time delay relay 86 may be inserted into the system toprovide the desired safety time for the specific burner which is beingignited. As is apparent from the foregoing description, the providedsystem not only assures ready shut-down or closing of the fuel valve butin addition assures cessation of the sparking transformer Within ashort, safe time period. Although the foregoing description has beenspecific with respect to a gas heated ironer, it is obvious that theprovided ignition system will function to advantage in any systememploying fuel in a manner similar to that above described.

While particular embodiments of this invention have been shown anddescribed, it will be understood, of course, that the invention is notlimited thereto since modifications may be made by those skilled in theart, particularly in light of the foregoing teachings. Therefore, it iscontemplated by the appended claims to cover any such modifications asincorporate those features which may be said to constitute the essentialfeatures of these improvements, within the true spirit and scope of theinvention.

I claim:

1. In a gas burner control assembly, an elongate burner having aplurality of burner tips spaced along the length of-said burner, meansfor supplying a combustible gaseous mixture along the length of saidburner for discharge through said tips, electrical ignition means forigniting the gaseous mixture discharging from the burner tip disposedadjacent one end of said burner, valve means for controlling the passageof gaseous mixture to said burner, adjustable timer means connected tosaid valve means and adapted to close said valve means after theexpiration of a preselected period of time; heat sensitive meansdisposed adjacent a burner tip at a second end of said burner oppositeto said one end and adapted to de-energize said timer means upon sensingheat at said second end whereby said valve means will remain open afterthe expiration of said preselected period of time; means for exhaustingproducts of combustion from the vicinity of said elongate burner, andmeans responsive to both a desired pressure in said means for supplyinga gaseous mixture and to proper operation of the exhausting means forsubstantially simultaneously opening said valve means, energizing saidignition means and energizing said timer means.

2. The assembly of claim 1 in combination with thermostat meanssensitive to the heat generated by said burner; said valve means beingresponsive to the condition of said thermostat means whereby said valvemeans is closed when a predetermined temperature is sensed by saidthermostat means.

References Cited UNITED STATES PATENTS 2,302,456 11/ 1942 McCollum 43171X 2,335,471 ll/1943 Ashcraft 431- X 2,399,673 5/1946 Hall 43166 X2,503,260 4/1950 Hall 431-74 3,056,398 10/ 1962 Kirk 431-31 X 3,064,71911/ 1962 Graves 43 l26 3,162,429 12/ 1964 La Pointe 43 l46 X 3,343,5859/1967 Eckelberry 43 131 3,393,037 7/ 1968 Giuifrida et al 431-31 XEDWARD G. FAVORS, Primary Examiner

